This application relates to an environmental control system for an aircraft which extracts both high and low pressure compressed air for uses on an aircraft.
Commercial aircrafts or jetliners typically employ an environmental control system to pressurize a passenger cabin of the aircraft and/or thermal anti-icing systems to provide heated air for anti-icing applications. Air supply to these systems is typically provided by bleed air extracted from or provided by a compressor of an aircraft engine. To meet pressure and/or temperature demands of the various aircraft systems, bleed air is often extracted from a high stage of a low-pressure compressor of the aircraft engine. For example, bleed air is often extracted from an eighth stage compressor of an aircraft engine. The pressurized bleed air is then often cooled via a precooler prior to providing the bleed air to a system of the aircraft (e.g., environmental control system). Thus, a portion of the energy spent by the engine to produce the bleed air is wasted when cooling the bleed air via the precooler. As a result, high-pressure bleed air extracted from the compressor may significantly reduce the efficiency of the engine.
To reduce extraction of bleed air, some known systems employ a turbo-compressor that receives ambient air from an atmospheric inlet. The turbo-compressor pressurizes the ambient air prior to supplying the various aircraft systems. However, the atmospheric inlet produces drag. Additionally, the atmospheric inlet is often susceptible to icing and, thus, requires an anti-icing system that increases costs and system complexity. Further, the compressor may have to be relatively large to produce a pressure change sufficient to power the systems of an aircraft.